2 stroke 49cc speed question

Discussion in '2-Stroke Engines' started by WillieB, Sep 2, 2010.

  1. WillieB

    WillieB New Member

    Hopefully simple question: How fast can a 194lb male go using a 2 stroke 49cc motor?

  2. bilboby

    bilboby Member

    Hi their,

    Well i'm 230lbs and riding a 49cc rear friction drive engine & have reached 20mph but it's a new engine + it's forever having niggley problems. I should point out that before i needed to peddle for uphill riding but with the friction engine now fitted such rides are a an uphill riders dream as one peddles less harder.

    Cheers & 73's
  3. geebt48cc

    geebt48cc Member

    MMmm, Well, I'm 6' 6" 250lbs, and with 48cc 2/stroke ='s right at 32mph on flat.
  4. 5-7HEAVEN

    5-7HEAVEN Guest

    I weigh the same as you and cruise at 35mph.

    It is not a simple question.
  5. WillieB

    WillieB New Member

    thanks for the input, its been helpful
  6. motorpsycho

    motorpsycho Active Member

    i'm 5'7, weigh 155 lbs, and my 49 cc 2 stroke is mounted to a 20" frame with 20" wheels and a 41 tooth sprocket.
    I can get 25-28 mph top speeds out of it, but it also has an expansion chamber, a high flow air filter, an ngk spark plug, a re-jetted carb. and upgraded spark plug wire.
    my top speed is limited because of my wheel / sprocket size, but 25 mph is pretty darn fast on a 20" bike.
    i also have an 80 c.c. 2 stroke, also on a 20" bike with 20" wheels, and a 41 tooth sprocket. I am getting right around 27 mph out of it, and it has a modified stock (long pipe) exhaust, high flow air filter, cns style carb that i re-jetted, upgraded spark plug wire, and an ngk spark plug.
    this engine is on an occ chopper, and the rear tire is 24" tall, as opposed to the rear cheater slick tire that's on my other bike, which is 21" tall. even tho both bikes have 20" rims and 41 tooth sprockets, the taller tire on my occ bike is giving me a tiny bit more top speed. in reality, the 49 cc and the 80 c.c. make about the same power (in my opinion), but the 49 cc seems to rev slightly faster, and higher than the 80 c.c., but the 80 c.c. seems to have more bottom end torque.
    my next change to both bikes is going to be a 36 tooth sprocket because the 41 tooth sprockets are still too big. I can cruise easy at 15 mph right now without either engine revving super high, but at top speed, both engines rev higher than i'd like them to.
  7. geebt48cc

    geebt48cc Member

    See, that's the reason I went with the 48cc, cause it's legal, and overall does the job.Uno, for a man that weighs 250+, it really holds it's own for a china made 48cc. It's got a slant head, but I'm interested in the bullet head.

    Do you guys know where I would find one for a 48cc Skyhawk?

    lol, I probably look like a hippo on this little bike, but who cares..........FUN is what it's all about for very little $$$$$$...........:eek:

  8. 5-7HEAVEN

    5-7HEAVEN Guest

    If you want improved acceleration and a longer-lasting engine, nothing comes close to a shift kit.

    No second chain/tensioner/rear sprocket issues.

    And then there's shifting thru 7 gears!:grin5:

    NOTHING on the MB can match that sensation for me!:grin5:

    Well, maybe starting the engine and the bike slowly rolling forward.:cool:
  9. HeadSmess

    HeadSmess Well-Known Member

    ok, heres the mathematical way.

    1 hp= 30,000ft/lbs /min

    or. move 1 pound 30,000 feet in a minute.

    this doesnt take into account wind resistance, friction, or inertia.

    so could be bs :p

    um. it really depends on what engine it is.... cus if you have ever jumped on a ktm 50.... thats 49cc of pure evil :eek: that will quite easily get 100kg going at 90km/h...
  10. motorpsycho

    motorpsycho Active Member

    yes, a ktm 50 is a monster, but a portion of that has to do with the gearing in the transmission and the final drive gear ratio.
    but, the ktm 50's make a ton more power than these little chinese motors ever will.
  11. aboudie19

    aboudie19 Guest

    I'm 5'8" 170lbs and I have a 49cc dirt bike I bought from Belmonte Bikes. When I first got it it was reaching a max speed of 22mph, but then I did some research and I added a Big Bore Kit 44mm for my bike. It's added about 5hp extra to my bike! Definitely feels faster than it was before but havent tested the exact speed yet. It's at least 3-5mph faster though.

    I bought the big bore kit for $59 from here:


    And I bought my 49cc Dirt Bike from the same website in case it matters:

  12. Steve Best

    Steve Best Well-Known Member

    Hey Aboudie19, can you get me an accurate measurement from bolt to bolt across your head or cylinder?
    Here are the measurements I am looking for:
    Can you find these measurements?
    Last edited: Sep 10, 2016
  13. skyash

    skyash Active Member

    I got a 44mmbigbore and its not the same but it measuresthe same and i get 50mm where the ? Is
  14. zippinaround

    zippinaround Active Member

    that big bore kit is for a mini moto engine , you have a mini moto eng on your bike?
  15. skyash

    skyash Active Member

    Yeah a pocket bike motor with a big bore kit installed on my push bike
  16. zippinaround

    zippinaround Active Member

    nice any pics?
  17. skyash

    skyash Active Member

    Its a 26inc bike with 20inc forks and wheels . Welded the seat post on the frame .pedals off a kids bike i made the tank made some clip on handle bars got a 52t sprocket lazer cut after having a 54t made up frist made a spacer for the forks to fit on welded a metal plate mount up welded a drive sprocket from a 66cc on the shaft of the pocket bike transfer box i use a 415 chain. ..after the frame broke in 2 places on the weekend i have started covering the frame with sheet metal and re welding everything. I all so made a new head for the engine you can see in the pics .the stock motor 2hp did 45kmh no problem the big bore 4hp one hits 60kmh no problem straight out the box played with it a little new carby spark plug and rocket key now gets 67kmh.. so i wood like a 50t sprocket. I just lightened the fly wheel opened the boost ports and transfer ports took a little off the top of the exhaust port.just need to finish the frame and put it back together. Then see what i hit.

    Attached Files:

  18. zippinaround

    zippinaround Active Member

    Looks cool im planning on making a full suspension with rack mounted mini moto engine , the one i have is stock but can get a brand new racing engine for about 90€ brand new compared to about 60€ for the big bore kit that includes a racing crank, can get the one without crank for about 35€ .

    Anyway i need to make my rack next but am gonna try using the normal chain 25h probably a bad idea really haha